1. Field of the Invention
The present invention relates to a head suspension for a disk drive installed in an information processing apparatus such as a personal computer.
2. Description of the Related Art
A hard disk drive (HDD) records and reproduces information to and from rotating magnetic or magneto-optical disks. The disks are supported with a carriage that is turned around a spindle by a positioning motor.
An example of the carriage is disclosed in U.S. Pat. No. 4,167,765. The carriage of this disclosure includes a carriage arm, a head suspension attached to a front end of the carriage arm, a head attached to the head suspension, and a slider attached to the head. The slider faces a disk. When the disk is rotated at high speed, the slider slightly floats from the disk, and an air bearing is formed between the disk and the slider.
FIG. 1 is a sectional view partly showing a hard disk drive having head suspensions according to a related art. The disk drive 101 has a carriage 105 that is turned around a spindle 103 by a positioning motor 107 such as a voice coil motor. The carriage 105 has a plurality of (four in FIG. 1) carriage arms 109, a head suspension 111 attached to a front end of each carriage arm 109, and a head 113 attached to a front end of each head suspension 111.
The carriage 105 is turned around the spindle 103, to move the heads 113 onto a target track on disks 115. Each head 113 includes a slider 117 to be positioned onto a target track on the disk 115 and a transducer (not shown) supported with the slider 117.
When the disks 115 are rotated at high speed, air enters between the disks 115 and the sliders 117 to slightly float the sliders 117 from the disks 115 and form air bearings between them.
FIGS. 2, 3A, and 3B show the head suspension 111. The head suspension 111 includes a load beam 119 made of a precision thin plate spring, a flexure 121 made of a very thin plate spring fixed to the load beam 119 by, for example, laser welding, and a base plate 123 fixed to a base of the load beam 119 by, for example, laser welding. The base plate 123 is attached to a suspension attaching face of the carriage arm 109.
Recent hard disk drives employ high-density disks and drive the disks at high speed. Such high-density disks involve narrow tracks, and therefore, vibration such as butterfly mode vibration of the head suspension 111 caused by air disturbance results in moving the head 113 away from a track center.
It is important, therefore, to control the amplitudes and frequencies of various resonance modes and air disturbance concerning the head suspensions 111 and carriage arms 109 between the actuator 107 and the sliders 117 in the disk drive 101. The recent high-density, high-speed disks require head suspensions of high rigidity and low spring constant.
To achieve the requirements, the load beam 119 of FIGS. 3A and 3B has a channel 125. The load beam 119 has a rigid part 119a that extends for a length L1 and needs high rigidity and a resilient part 119b that extends for a length L2 and needs a low spring constant. To simultaneously satisfy these needs, the resilient part 119b is thinned and edges of the rigid part 119a are shaped into the channel 125 to compensate the thinness of the rigid part 119a that is restricted by the thinness of the resilient part 119b. 
The channel 125 provides another function when the head suspension 111 is installed into the disk drive 101.
FIG. 4 shows a comb 127 used when installing a head suspension module into a disk drive. The head suspension module consists of a plurality of head suspensions arranged at regular intervals. In FIG. 4, the comb 127 has two teeth 129 and 131 corresponding to the number of head suspensions included in the module. FIG. 5 shows an example of the head suspension module. This module consists of four head suspensions 111.
The teeth 129 and 131 of the comb 127 are inserted into the head suspension module as shown in FIG. 5 to maintain a given space between the adjacent sliders 117 (FIG. 1). The comb 127 enables horizontally to insert the head suspensions between the disks 115 (FIG. 1) so that the sliders 117 may face the disks 115. After the head suspension module is fixed at a proper position in the disk drive 101, the comb 127 is removed from the head suspension module. In this way, the comb 127 is used to smoothly insert a module of head suspensions between disks in a disk drive.
When inserting the teeth 129 and 131 of the comb 127 between the head suspensions 111, curves 125a (FIG. 3B) of the channel 125 serve as guides to reduce friction between the load beams 119 and the teeth 129 and 131.
The channel 125, however, causes air disturbance when the disks 115 are rotated at high speed, to flutter the load beams 119.
To solve the problem, this applicant has proposed a head suspension for a disk drive in Japanese Patent Application No. 11-263705. This head suspension simultaneously realizes high rigidity for a rigid part (119a) and a low spring constant for a resilient part (119b) by separating the resilient part from the rigid part and by making the rigid part thicker than the resilient part. The rigid part has no bends, and therefore, causes no air disturbance and load beam fluttering when disks are rotated at high speed.
Instead of having no bends, the rigid part of the disclosure has sharp edges 133 as shown in FIG. 6. When the tooth 129 of the comb 127 is inserted between the head suspensions, the edge 133 of the rigid part 119a scrapes the teeth 129, and the scraped dust spreads over the disks 115 to hinder the operation of the disk drive. In addition, the sharp edges 133 quickly wear the teeth of the comb 127, thereby deteriorating the durability of the comb 127.